//根据下拉框的选择改变表单提交的目标链接
function setChoice() {
    if (document.getElementById("choice").selectedIndex === 1) {
        document.getElementById("form").action = "/login?identity=customer";
    } else if (document.getElementById("choice").selectedIndex === 2) {
        document.getElementById("form").action = "/login?identity=salesman";
    }
}
//警告框
function judgeValidity() {
    if (document.getElementById("choice").selectedIndex === 0) {
        alert("请选择您的身份！");
    }
}
